As the manufacture of semiconductor devices becomes more complicated and the integration density of semiconductor devices highly increases, there is a need to form fine patterns. Furthermore, with regard to 1-Gigabit or more semiconductor memory devices, a pattern size having a design rule of 0.1 μm or less is needed. Therefore, the use of conventional photoresist materials for a KrF eximer laser (248 nm) is limited. For this reason, lithography techniques using an ArF eximer laser (193 nm) or an F2 eximer laser (157 nm), which are shorter-wavelength energy sources than a KrF eximer laser, have emerged. Lithography processes using an F2 eximer laser (157 nm) need resist materials having a new structure.
However, ArF and F2 resist materials have many problems due to their structural limitations as compared with i-line or KrF resist materials, which include pattern collapse due to the fine pattern size and poor resistance to dry etching. Therefore, there is a need to develop new resist materials and processes therefor.
In a photolithography process for manufacturing highly integrated semiconductor devices, the application of a bi-layer resist (BLR) process ensuring dry-etching resistance and formation of high aspect ratio patterns, which eliminates drawbacks of a single layer resist process, is advantageous.
In the BLR process, binary chemically amplified resists have been widely used, which are composed of a silicon-containing polymer having in its backbone silicon atom substituents and a photoacid generator (i.e., positive chemically amplified resists). Also, the development of highly sensitive resist materials for BLR processes using a short-wavelength light source has been focused on positive chemically amplified resists. However, silicon-containing resist compositions developed to date for BLR processes have strong hydrophobicity and exhibit poor adhesion to an underlying layer. Also, it is difficult to control the amount of silicon to an appropriate level for resist materials.
The use of positive resists is limited in forming isolated patterns for high-speed, high-performance DRAMs. A lithography process for manufacturing 1-Gigabit or more DRAMs requires the use of a phase shift mask. In designing phase shift masks, it is more advantageous to use negative resists than positive resists. Therefore, there is an urgent need for the development of negative resists that are highly transparent for an exposure light source having a short wavelength and exhibit high resolution and high dry-etching resistance characteristics.